Hi there! I'm developing quite a big project using the latest Keil3 IDE C166, so I decided to split up the code into smaller libraries to speed up the compilation. Now there is quite a set of libraries which depend on each other. For example, ProjectX uses Library2 and Library2 uses Library1. The strange thing is the compilation of Library2. The compiler does not complain about any missing functions, it just shows the following warning: LIBRARY2.C(138): warning C140: 'TestFunction' undefined; assuming 'extern int TestFunction()' In the example above the function "TestFunction" does not exist in Library1. So why doesn't the compiler throw a compilation error on me? The next problem to solve is the c-source-level debugging of library code. In a different thread I found the "SET SRC = Path" command to be entered in the debug command window, so that the debugger searches in the specified path for the concerning library source files. This would be ok but the source codes of each library is placed in a different location. Is there a way to automatically provide the source path for each library source code or do I have to enter the source path by using the "SET SRC = " command each time I would like to debug it? Thanks in advance, Axel.